Precious Moments Assassinate 100 players while invisible as the Ninja; obliterate 100 enemies with the Pirate's cannon balls; chew 100 enemies as the Giant in online games

This trophy requires you to kill 100 enemies be they player or NPC using each classes special ability. Note kills in soccer games will not be recorded.

For the Ninja (perhaps the hardest) I'd recommend you stick to killing NPC's or player mage / priest characters. Start off with a few hits in melee, then once you've gotten the enemy down to 4 hearts or less hit enter stealth and finish them off with a last melee hit. Alternatively you can sneak into the enemy base and kill afk / idle villager class characters.

The Pirate is much easier, simply fire your cannon ball whenever you have a group of enemies around, due to the high damage and large AoE you can expect a kill or two without any real effort. For better results allow another pirate to fire his cannonball at a group of enemies first, then immediately follow yours, two cannon balls will kill just about everything in its area.

Lastly, the Giant will have the easiest time here, all you need to do is get close to an enemy and hit the button to automatically kill any non-giant class character. The fastest, safest and most enjoyable method I've found is to team up with a friend and have him follow you around constantly healing you, then simply walk into the enemy base and smash and chew the enemy, however this is far easier if you play in a private game versus NPCs.

You can check your progress in the stats screen (Bragging rights/Why I'm awesome).

Ninjas Are Better Than Pirates Assassinate 20 Pirates within a single game as a Ninja in online games

This trophy is virtually impossible to get during regular play therefore boosting is the only really viable way to attain it.

Simply start a private 1v1 rescue the princess game on any map have your friend select the Pirate class and walk just outside his castle gates, meet him there as a Ninja.

Hit his health down till their health bar appears orange (under 4 hearts) then quickly press to enter stealth mode, stand next to the Pirate, hold to target and press once. He should die, then simply rinse and repeat 19+ more times. After you're satisfied you've gotten at least 20 kills in this manner simply end the game and the trophy should pop.

Warning: try to kill the enemy before he sits down and starts to regain health as this may nudge him over the 4 heart threshold.

Pirates Are Better Than Ninjas Annihilate 20 Ninjas within a single game as a Pirate in online games

Virtually identical to Ninjas Are Better Than Pirates - only 20 kills are required with the Pirates cannon ball attack on Ninja targets - see above.

The only change (besides classes) that you should be aware of is that the Pirates cannon ball is aimed a little differently. Hold down when the special meter is filled and you'll see a black X shape aim this area over your partner, releasing the button will call in the cannon ball to this location.

Again you should hit your enemy a few times with your sword or a few pistol shots to take his health down till his health bar appears orange, however as there is a slight delay between calling in the cannon ball and it actually hitting I recommend you have your friend jump up and down or keep moving to avoid him sitting down and regaining health.